Synthesis and properties of a silyl(silylene)ruthenium complex: activation barrier of the Ru=Si bond rotation and facile replacement of the methyl groups with alkoxy groups of a silyl ligand

A silyl(silylene)ruthenium complex, Cp* Ru(CO)(=SiMes ₂)SiMe₃ (2), was synthesized by the reaction of Cp*Ru(CO) (py)Me with HSiMe₂SiMeS₂Me (Mes = 2,4,6trimethylphenyl). In contrast to its iron analogue Cp*Fe(CO)(= SiMes₂) SiMe₃ (1), which we reported previously, 2 exhibits a fluxional behavior that involves rotation around the Ru=Si and Si-C(mesityl) bonds. The activation parameters for the M=Si bond rotation were determined for the first time using line-shape analysis of the variable-temperature ¹H NMR spectra of 2. Complex 2 underwent a facile alkoxylation reaction on the silyl ligand with ROH (R = Me or Et) in the presence of R′NC (R′ = ^tBu or Xyl= 2,6-dimethylphenyl) to afford Cp*Ru(CO) (CNR′)[Si(OR)₃] and MeS ₂Si(OR)H in high yields at room temperature, with cleavage of all three Si-C bonds.